This invention relates to an axle assembly having multiple wheels at each end of an axle housing, and more specifically, the invention relates to dual wheel assemblies in which one wheel is permitted to rotate relative to the other wheel.
Axle assemblies having dual wheels on either end of the axle have been used to increase the load bearing capability of heavy duty vehicles. Typically the pair of wheels on each end of the axle assembly are secured together so that they rotate together about an axis. Some heavy duty vehicles, such as lift trucks, undergo numerous turning maneuvers which wear the tires significantly. The tire wear is caused when the tires scrub, or drag, since the wheels that are secured together must travel different distances at the inside and outside of the turning radius. Tire wear and maintenance on heavy duty lift trucks due to scrub cost thousands of dollars annually per vehicle.
Dual wheel assembly designs have been proposed that permit the wheels to rotate relative to one another to reduce scrubbing during vehicle turns. One wheel assembly has provided a pair of wheels on an end portion of an axle housing that is fluidly driven by the axle shaft. The axle shaft drives an impeller that fluidly drives a turbine connected to each wheel hub. While the wheel assembly permits slip between the wheels during vehicle turns, there is not a mechanically driven wheel to ensure traction by one wheel. Furthermore, by not providing at least one mechanically drive wheel, the overall efficiency of the dual wheel assembly is reduced. Therefore what is needed is a dual wheel assembly having a fluid coupling with a mechanically driven wheel that permits slip during vehicle turns.
The present invention provides a dual wheel axle assembly for a vehicle. The assembly includes an axle housing having an axle shaft arranged within the axle housing.
The axle shaft defines a rotational axis. A first wheel hub is supported on an end portion of the axle housing and is mechanically coupled to the axle shaft. A second wheel hub is supported on the end portion adjacent to the first wheel hub. A fluid coupling is interconnected between the axle shaft and the second wheel hub. The fluid coupling has fluid for fluidly driving the second wheel hub through the axle shaft and permitting the second wheel hub to rotate about the rotational axis relative to the first wheel hub during a vehicle turn.
Accordingly, the above invention provides a dual wheel assembly having a fluid coupling with a mechanically driven wheel that permits slip during vehicle turns.